Research On Nano Array Anode Electrocatalysts For Direct Methanol Fuel Cell

The lack and irrationality using of energy has done serious damage to hunman's living environment and the nature environment. The fuel cell as an electricity generated equipment which can convert fuel's chemical energy to electricity power directly not by burning but by electrochemistry way is hopeful to become the best,clean,high efficient electricity generated technology. Direct methanol fuel cell as one of the important embranchment of the fuel cells have gained amount of attentions within the last years due to its high power density, simple operation, and portability. As a green and renewable fuel,methanol is less toxic and is available from crop ferment. Because of all these disadvantage,DMFC is hopeful to be used in convenient electrical source,electromotor and so on. platinum is usually used as anode catalyst, However,in DMFC,during oxidation of methanol some intermediate species or adsorption residues such as aldehyde,carboxylic acid and particular CO can decreased the catalytic activity of platinum, which was called poisoning of catalyst, This makes the development of anode electro-catalysts for methanol electro-oxidation a great challenge task. in addition to high cost of platinum, developing an electrode containing less platinum but high catalytic activity with large surface is meaningful and interesting.The preparation of a series of nano-array electro-catalysts and the electro-oxidation of methanol on nano-array electrode-catalysts were studied by electrochemistry measurement. The catalysts were characterized by XPS,SEM,XRD and TEM technique. The mechanism of methanol oxidation on those catalysts has also been discussed. Some results has found they displayed high activity towards methanol oxidation.In this thesis, the development and classification of fuel cell have been reviewed. The principle,research and application of direct methanol fuel cell especially the research of its'anode catalyst have been introduced in this part. The nano electro-catalytic material and their application foreground have also been reviewed, from which the research ideas of the present work are derived.The main cotents and innovations of this thesis are as follows: 1. Pt,PtRu,PtPd,PtCo,PtBi,PtSn,PtRuPd,PtRuCo modified GC electrodes were prepared by electrochemistry method and the Pt-based ternary alloy show higher performance for methanol electro-oxidation than Pt-based duality alloy,Pt-based duality alloy exhibited higher performance than Pt-GC electrode and Pt foil electrode. Different concentration of the electrolyte solution were studied,and the best proportion of all the modified electrodes were compared each other.2. We prepared Pt-alloyed hollow spheres in H2PtCl6,RuCl3,,PdCl2,CoSO4 solution by using Bu4NBr as the template,NaBH4 as the reduction,5%Nafion solution was added to the hollow spheres and they were mixed ultrasonically and then were spreaded on the surface of Glassy carbon electrode as the anode electrode towards methanol oxidation. All of the modified electrodes displayed high catalytic toward the oxidation of methanol, while the cost of nobel metal was reduced. This can be ascribe to the special stucture and large surface area of hollow spheres. Among all these hollow spheres modified electrodes, PtRuPd hollow spheres modified electrode was considered as the best catalyzer,not only because of the effect of Pd and Ru element, but also for the perfect PtRuPd hollow structure.3. We have prepared AAO template by anodizing a high-purity Al foil in an acid solution using a two step process. Pt-based Composite nanowires were made by potentiostatic control and pulsed deposition technique in AAO template with a pore diameter of about 60 nm. Pt-alloyed nanowires array electrodes exhibit greatly enhanced performance in terms of the current density toward methanol oxidation.We believe that the current enhancement and onset potential are most influenced by electronic effects whereas their immunity to CO poisoning is largely controlled by the geometric and structural factors. It is believed that the enhanced activity of the Pt-alloyed nanowires is surely throwing some light on the research and development of effective DMFC catalysts.